Tessellate/src/hex.js

import Point from './point.js';

function computeY(x, z) {
	return -x - z;
}

// convert real numbers to integers:
//   round off coords
//   throw out whichever one changed the most
//   re-establish "x + y + z = 0"
function roundOff(hex) {
	let rX = Math.round(hex.x);
	let rY = Math.round(hex.y);
	let rZ = Math.round(hex.z);

	let xDiff = Math.abs(rX - hex.x);
	let yDiff = Math.abs(rY - hex.y);
	let zDiff = Math.abs(rZ - hex.z);

	if ((xDiff > yDiff) && (xDiff > zDiff)) {
		rX = -rY-rZ;
	}
	else if (yDiff > zDiff) {
		rY = -rX-rZ;
	}
	else {
		rZ = -rX-rY;
	}

	hex.x = rX === -0 ? 0 : rX;
	hex.y = rY === -0 ? 0 : rY;
	hex.z = rZ === -0 ? 0 : rZ;

	return hex;
}

export default class Hex extends Point {
	static qrToCube (q, r) {
		return {
			x: q,
			y: computeY(q, r),
			z: r,
		};
	}

	static cubeToEvenR ({x, y, z}) {
		const col = x + (z + (z & 1)) / 2;;
		const row = z;

		return {col, row};
	}

	static evenRToCube (col, row) {
		const x = col - (row + (row & 1)) / 2;;
		const z = row;
		const y = -x - z;

		return new Hex(x, y, z);
	}

	static cubeToEvenQ ({x, y, z}) {
		const col = x;
		const row = z + (x + (x & 1)) / 2;

		return {col, row};
	}

	static evenQToCube (col, row) {
		const x = col;
		const z = row - (col + (col & 1)) / 2;
		const y = -x - z;

		return new Hex(x, y, z);
	}

	constructor() {
		super();

		if (arguments.length === 1) {
			const {q, r, s = -q - r} = arguments[0];
			const {x, z, y = -x - z} = arguments[0];

			this.x = !isNaN(q) ? q : x;
			this.y = !isNaN(s) ? s : y;
			this.z = !isNaN(r) ? r : z;
		}
		else if (arguments.length === 2) { // hex = Hex(q, r);
			this.x = arguments[0];
			this.z = arguments[1];
			this.y = computeY(this.x, this.z);
		}
		else if (arguments.length === 3) { // hex = Hex(x, y, z);
			this.x = arguments[0];
			this.y = arguments[1];
			this.z = arguments[2];
		}

		roundOff(this);
	}

	getX() {return this.x;}
	getY() {return this.y;}
	getZ() {return this.z;}

	setX (newX) {this.x = newX; return this;}
	setY (newY) {this.y = newY; return this;}
	setZ (newZ) {this.z = newZ; return this;}

	moveX (byX) {this.x += byX; return this;}
	moveY (byY) {this.y += byY; return this;}
	moveZ (byZ) {this.z += byZ; return this;}

	getQ () {return this.x;}
	getR () {return this.z;}

	setQ (newQ) {
		this.x = newQ;
		this.y = computeY(this.x, this.z);
		return this;
	}

	setR (newR) {
		this.z = newR;
		this.y = computeY(this.x, this.z);
		return this;
	}

	moveQ (byQ) {
		this.x += byQ;
		this.y = computeY(this.x, this.z);
		return this;
	}

	moveR (byR) {
		this.z += byR;
		this.y = computeY(this.x, this.z);
		return this;
	}

	getPoint () { return {x: this.x, y: this.y, z: this.z}; }

	setHex (newHex) {
		this.x = newHex.x;
		this.y = newHex.y; 
		this.z = newHex.z;
		return this;
	}
	moveHex (byHex) {
		this.x += byHex.x;
		this.y += byHex.y;
		this.z += byHex.z;
		return this;
	}

	subtractHex (hex) {
		this.x -= hex.x;
		this.y -= hex.y;
		this.z -= hex.z;

		return this;
	}

	getAxial () {return {q: this.x, r: this.z};}

	setAxial (newAxial) {
		this.x = newAxial.q;
		this.z = newAxial.r;
		this.y = computeY(this.x, this.y);
		return this;
	}

	moveAxial (byAxial) {
		this.x += byAxial.q;
		this.z += byAxial.r;
		this.y = computeY(this.x, this.z);
		return this;
	}

	distance (hex) {
		return Math.max(Math.abs(this.x - hex.x), Math.abs(this.y - hex.y), Math.abs(this.z - hex.z));
	}
}